Lifting-jack



(No Model.) f

4 i J. DAWSON.-

` 'LIFTING JACK. No.' 278,317. PatentedvMay 29,1883.

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UNITED STATES PATENT FFICE.

JAMEs nAwsomoE sAN FEANcIsoo, CALIFORNIA.

LiF'rlNo-JACK.

SPECIFICATION forming part-of Letters Patent No. 278,317,dated May 29,1883, l

Application filed February 5, 1883. (No model.)

To all whom it 'may concern: t

Be-itknown that I, JAMES DAWSON,` acitizen of the United States,residing at San Francisco, in the county of San Franciscoand State ofCalifornia, have finvented certain new and useful Improvements inLifting-Jacks; and I do declare the following to bea full, clear, andexact description of the invention, such as will enable others skilledin the art towhich it ap- .pertains to make and use the same, referencebeing had to theaccompanying drawings, and

IS `lifting-jacks,V and has for its object the moveto the letters andfigures of reference marked thereon, hich form a part of thisspecification. l

My invention relates to improvements in ment of the lifting-bar usuallyemployed in this class of devices by means `of cogs, gearwheels, and acrank-arm, the arrangement and operation of which will be more fullypointed out in the specification and claims.

Figure l is a side view of Inj-'improved lifting-jack, showing the sideof casing, and by Fig; 2 is-a 1ony is a detail view of the bushings.

`A represents a metallic shell,` preferably cast rectangular in form,`and having a. chamber, a, of rectangular form,in its upper end,

and a. similar chamber a in its lower end.l

These chambers a and c are formed with angular apertures through theircenters for the i j passage of the lifting-bar B,and are of sufcientwidth and depth to admit the friction-- rollers b and b. These rollersare formed to play loosely inside the chambers aand at', and arearranged to work against the sides of the chambers aand c andagainst thesides and rear of the lifting-bar B. The lifting-bar B is formed ofmetal, rectangular in shape, and has one edge serrated or grooved outcrosswise to form teeth or cogs. `The purpose of "this formation, aswill be more fully pointed out, is to gear with cog-wheels when moved npor down through the casing A by gearwheels andzpinions.

Each side of the casing is perforated at two points equidistantfromeachother,and on the d so outer side of the casing A these perforations lterminate in hollow projections c and c. In-

side these projections bushings ci and d' are placed to form thejournals or bearings for the shafts G and C. These bushings d and d areformed to pass from the outer side of the projections c and c through tothe inner sides of the casing A, and are held in place by setscrews eand c. The projections o and c are connected by stiffening-ribs f, thepurpose of` mesh with and `operate the toothed rack-bar or lifting-barB.

0n the outer side of gear-wheel g, and near the'inside of casing A, issecured on shaft O a larger gear-wheel, g.

Shaft U is formed with an angular projection 0n its outer end for thereception of a crankarm or other device by which movement iscommunicated to said shaft. On the inside of the casing A, and directlyopposite wheel g, is secured on shaft G a small gear-wheel, h, and ofsufficient size to mesh or gear with wheel g.

The operation `is-as follows: Lifting-bar B is inserted through theapertures in chambers o anda through the casing with the teeth or cogsmeshing with the teeth or cogs of gearwheel g, when power is applied tothe shaft Cby means of its angular end, when the bar B is moved up ordown,"as desired.

Having thus described my invention, what I desire to secure by LettersPatent isl small gear-wheel, g, the purpose of which is tof l. Thecombination of the casing A, having.

chambers a and a', holding friction-rollers b and b', the shafts C andC', bushings.` d and d', gear-wheels g, g', and h, with theliftingbar'B, substantially as shown and specified.

I 2. A lifting-jack provided with a casing, A, having chambers c and a',containing frictionrollers against which the lifting-bar moves whenoperated by shafts and gear-wheels, substantially as shown andspecified.

3. Thebushingscl and d', formed as described,

and adapted to pass into Ihe projections cand c', and retained in placeby set-screws, substantially as shown.

In testimony whereof I affix my signature in presence of two witnesses.

JAMES DAWSON.

Witnesses GEO. H. NoRnIs, J. J. KELLY.

